Numerical Analysis of the Effect of an Inverted Cone Angle on the Penetration Behavior of the Jack-Up Leg Foundation for Offshore Wind Turbines in Uniform Clay

The design of a jack-up leg foundation as a fixed substructure for offshore wind turbines requires a thorough investigation of the effects of the detailed spudcan geometry, leg type, and soil condition on the penetration resistance. Therefore, this study evaluated the effect of the bottom-shape inverted cone angle of the spudcan on penetration resistance in uniform clay using large-deformation finite element analyses. The soil was idealized as a homogeneous, elastic, perfectly plastic material obeying the Mohr–Coulomb yield criterion. A numerical analysis was performed using the Coupled Eulerian–Lagrangian technique. A complete parametric study was performed to quantify the influence of undrained shear strength, cone angle, and roughness. The results showed that the cone angle and roughness affected the penetration resistance, and a higher cone angle resulted in higher penetration resistance. Moreover, the leg type and soil backflow affected the ultimate bearing capacity factor. As a foundation for offshore wind turbines, this study proposed that a spudcan connected to a cylindrical pile leg with cone tip angles greater than 150° and 120° can be used in stiff and soft clays, respectively, as a substitute for a pile foundation.